Increase a number by a percentage. Enter the starting value and the percent to add.
Usage Tip
To add a percent fast, multiply by 1 plus the decimal: +20% is times 1.2, +50% is times 1.5. To reverse a percent increase, divide rather than subtracting the same percent.
Result = value + increase
Stacked increases compound — two 10% raises is a 21% increase, not 20%.
Successive increases compound on the new total each time, not the original.
A percent increase and the percent decrease that undoes it are different numbers — up 25% then down 25% does not return to the start.
To increase a number by a percentage, multiply it by one plus the percentage written as a decimal. Raising 80 by 25 percent gives 80 times 1.25, which is 100. This is the calculation behind price rises, markups, salary increases, and growth in a quantity or a population.
Percentage changes apply to the current value, so two successive increases of 10 percent give a total increase of 21 percent, not 20. The percentage is also relative to the starting value, so a rise from 50 to 75 is a 50 percent increase, but a fall from 75 back to 50 is only a 33 percent decrease. Always be clear about what the percentage is measured against.